1. Field of the Invention
The present invention generally relates to image processing apparatuses and, more particularly, to an image-processing apparatus which converts read image into recordable image signal after changing the read image to digital image signals.
2. Description of the Related Art
Conventionally, multi-function apparatuses provided with a plurality of functions, such as a so-called copy function including reading of an image, a record output or transmission and reception of image data, a facsimile function, a printer function, a scanner function, etc., are known. A conventional multi-function apparatus (MFP) 100 shown in FIG. 1 comprises a facsimile control unit (FCU) 101, a printer control unit (PCU) 102, a motherboard 103, a reading unit 104, an image-processing unit 105, a video control part 106, an imaging unit 107, a memory control unit 108, a system controller 109, a random access memory (RAM) 110 and a read only memory (ROM) 111. The PCU 102 comprises, as shown in FIG. 2, a memory access control part (IMAC) 121, a network interface (I/F) 122, a system controller 123, a local bus interface (I/F) 124, a parallel bus interface (I/F) 125, a memory group (MEM) 126 and a serial bus interface (I/F) 127.
In the multi-function apparatus. (MFP) 100, after the reading unit 104 optically reads an image of an original and changes the read image into a digital image signal, the reading unit 104 outputs the digital image signal to the image-processing unit 105. The imaging unit 107 forms a reproduction image on a transfer paper based on the digital image signal from the video bus control part 106.
The image-processing unit 105 applies various image quality processes, such as correction of image degradation in the reading system of the reading unit 104 and gradation reproduction by an area gradation method, to the image signal, and outputs the processed image signal to the video control part 106. The video control part 106 performs a bus control, and arbitrates an incoming signal from the image-processing unit 105, an output signal to the imaging unit 107, an input-and-output signal to the memory control unit 108, and an input-and-output signal with the FCU 101 and the PCU 102 which are external application units connected through the motherboard 103.
An external extension application unit can connect a plurality of applications to the motherboard 103. Each application has a CPU and a memory, and functions as an independent unit. For example, the FCU (facsimile control unit) 101 and the PCU (printer control unit) 102 correspond to the applications. Regarding the job using a memory, such as image rotation by the copy function, after the MFP 100 stores the image data from the image-processing unit 105 in the memory control unit 108 via the video control part 106 and performs image rotation processing, the MFP 100 carries out image reproduction in the imaging unit 107 via the video control part 106. The MFP 100 carries out the series of controls by the system controller 109. On the other hand, regarding a deployment process on the memory of the printer output image by the PCU 102, the system controller 109 and the memory control unit 108 do not use the MFP 100, but uses uniquely the system controller 124 and the memory group 126 provided in the PCU 102 shown in FIG. 2.
In the PCU 102 shown in FIG. 2, the system controller 124 controls an operation of the entire PCU 102 so that the PCU 102 operates as a single unit as a whole. That is, the memory which can be used by the PCU 102 is only the memory group 126 inside the PCU 102. Such a composition of the PCU 102 is the same as the FCU 101. If data is sent to the PCU 102 via a network, print output request data is taken in the IMAC 121 through the network I/F 122.
When a general-purpose serial bus connection is used, the system controller 123 receives the print output request data supplied to the IMAC 121 via the serial bus I/F 127. Usually, a plurality of kinds of interfaces are provided as the general-purpose serial bus I/F 127 so as to cope with interfaces such as USB, IEEE1284 and IEEE1394. The system controller 123 develops the received print output request data to image data in an area within the MEM 126. At this time, font data of a font ROM (not illustrated in the figure) connected to the local bus concerned is referred to via the local bus I/F 124 and a local bus.
A serial bus connected to the serial bus I/F 127 is also provided with an interface (I/F) for data transmission with an operation part of the MFP 100 in addition to an external serial port for connection with a personal computer. Unlike print deployment data, the operation part of the MFP 100 communicates with the system controller 123 via the IMAC 121.
The system controller 123 controls reception of the processing procedure from the operation part and the display of the state of the system on the display part. The local bus connected to local bus I/F 124 is connected to the ROM and RAM required for control of the controller unit. Font data is input through the local bus and used for image deployment.
In the above-mentioned conventional multi-function apparatus (MFP), a memory is not used effectively and communization of a control mechanism including extended units is not made. That is, each of the facsimile control unit (FCU) and the printer control unit (PCU) has individually a system control module, a memory module and a memory control module. Accordingly, each control unit performs a similar control separately, and, thereby, effective use of resources is not achieved. Therefore, the apparatus is enlarged, and a cost is increased. Moreover, it is necessary to improve for increasing a processing speed.
Moreover, in the above-mentioned multi-function apparatus (MFP), in order to realize a high-quality image by a high-densification of dots, it has been suggested to perform a dot position control of writing. This is for the reason that a single dot reproduction with high-density dots needs a high technology, and, on the other hand, a stable and smooth gradation can be obtained by concentrating dots. However, depending on the kind of image, a very thin line, for example, is crushed when dots are concentrated. In such a case, it is necessary to perform a signal processing to cause a single isolated dot reproduced.
On the other hand, it has been suggested to attain a high quality output image by performing writing with a higher density than a reading density. For example, a process has been suggested to read by 600 dpi and write by 1200 dpi. If a single pixel of 600 dpi is converted into five values by halftone processing, the pixel data becomes 33-bit data. If this data is converted into a binary value of 1200 dpi by a high-density conversion, the data becomes 4-bit data. That is, an amount of image data increases by the high-densification conversion. Furthermore, when information of the above-mentioned pixel arrangement is added, the amount of information increases further and there is a problem in that a processing speed is decreased. Japanese Laid-Open Patent Application No. 6-12112 discloses a technology to reduce an amount of data by encoding image data. However, the technology disclosed in Japanese Laid-Open Patent Application No. 6-12112 relates to an exchange of image data with external equipment, such as a printer or a facsimile machine, and does not relate to encoding of high-density data for data transmission inside a processing apparatus.